In the fields of displays for use in television receivers and information terminals, studies have been made for replacing conventional mainstream cathode ray tubes (CRT) with flat-panel displays which are to comply with demands for a decrease in thickness, a decrease in weight, a larger screen and a high fineness. Such flat panel displays include a liquid crystal display (LCD), an electroluminescence display (ELD), a plasma display panel (PDP) and a cold cathode field emission display (FED). Of these, a liquid crystal display is widely used as a display for an information terminal. For applying the liquid crystal display to a floor-type television receiver, however, it still has problems to be solved concerning a higher brightness and an increase in size. In contrast, a cold cathode field emission display (to be sometimes referred to as “display” hereinafter) uses cold cathode field emission devices (to be sometimes referred to as “field emission device” hereinafter) capable of emitting electrons from a solid into a vacuum on the basis of a quantum tunnel effect without relying on thermal excitation, and it is of great interest from the viewpoints of a high brightness and a low power consumption.
As one example of the above field emission device, FIG. 26 shows a schematic partial end view of a filed emission device as shown in FIG. 2 to JP-A-9-90898.
In this field emission device, an insulating layer 2 is deposited on a substrate 1, and a control electrode (gate electrode) 3 made of a metal thin film is stacked on the insulating layer 2. A single cavity (opening portion) or a plurality of cavities (opening portions) is/are formed in the insulating layer 2 and the control electrode 3, and an emitter (electron emitting portion) 4 having the form of a cone is formed therein. An insulating layer 5 and a focus electrode 6 are stacked on the control electrode 3 excluding vicinities of the emitter 4. The substrate 1, the insulating layer 2, the control electrode 3, the emitter 4, the insulating layer 5 and the focus electrode 6 constitute a micro cold cathode (field emission device) 7, and a single micro cold cathode or a plurality of micro cold cathodes constitutes or constitute a cold cathode 15. In effect, electron beams 8 emitted from the emitter (electron emitting portion) 4 collide with an anode (anode electrode) 9, and flow in an anode-electrode power source (anode-electrode control circuit) 10 that generates positive voltage.
A voltage to be applied to the control electrode (gate electrode) 3 is generated in a control-electrode power source (gate-electrode control circuit) 17, and a voltage obtained by potential-dividing the voltage to be applied to the control electrode 3 with a variable resistor is applied to the focus electrode 6. As a result, the ratio of the voltage of the control electrode 3 and the voltage of the focus electrode 6 is constantly maintained at a value set with the variable resistor 14. When the focus state in a certain beam current quantity is adjusted with the variable resistor 14, a nearly equivalent focus state is maintained even if the electron beam current set value taken out from the emitter 4 is changed with an output voltage of the control electrode power source 17.
Meanwhile, in such a display, the distance between the anode (anode electrode) 9 and the focus electrode 6 is approximately 1 mm at the largest, and an abnormal discharge (vacuum arc discharge) is likely to occur between the anode 9 and the focus electrode 6. When an abnormal discharge occurs, the voltage of the focus electrode 6 or the control electrode (gate electrode) 3 abnormally increases, so that display performance is impaired in display quality, and further that the field emission device (control electrode 3, emitter 4), the focus electrode 6 and the anode (anode electrode) 9 may be damaged.
In a mechanism in which a discharge takes place in a vacuum space, first, electrons and ions that are emitted from the field emission device under a strong electric field work as a trigger to cause a small-scaled discharge. And, energy is supplied to the anode electrode 9 from the anode-electrode power source (anode-electrode control circuit) 10, the anode electrode 9 is locally temperature-increased, and an occluded gas inside the anode electrode 9 is released, or a material constituting the anode electrode 9 is caused to vaporize, so that the small-scaled discharge presumably grows to be an abnormal discharge. Besides the anode-electrode power source (anode-electrode control circuit) 10, energy accumulated in an electrostatic capacity formed between the anode electrode 9 and the field emission device may possibly work as a source for supplying energy that promotes the growth to the abnormal discharge.
For inhibiting the abnormal discharge (vacuum arc discharge), it is effective to control the emission of electrons and ions which trigger the discharge, while it is required to control the particles extremely strictly therefor. In a general production process of the cathode panels or the anode panels or the display panels using the anode panels or the cathode panels, practicing the above control involves great technical difficulties.
It is therefore an object of the present invention to provide a cold cathode field emission display that is so structured to be capable of inhibiting the occurrence of critical damage caused by energy, which is generated by an electrostatic capacity between the anode electrode and the field emission device, on an anode electrode or an electrode constituting the cold cathode field emission device even when a discharge takes place between the electrode constituting the cold cathode field emission device and the anode electrode.